Oil pump for a motor compressor

ABSTRACT

The invention relates to a lubricating system for a motor compressor assembly. The assembly has an oil sump and the motor compressor unit has vertically extending shaft means with a central lubricating bore, the lower part of the shaft means being disposed in the sump with the mouth of the bore being in fluid communication with the lubricating oil in the sump. The mouth of the shaft bore is provided with a propeller to effect an increased rate of lubricating oil delivery.

United States Patent Leffers et al. 1 May 23, 1972 OIL PUMP FOR A MOTOR[56] References Cited COMPRESSOR UNITED STATES PATENTS [72] Inventors:Hans Ulrik Leffers; Bendt Wegge Romer, 2,835,437 5/1958 Boynton..184/6.l6 both of Augustenborg; Knud vagan 2,809,872 10/1957 Wamer....jom, Nordborg of Denmark 2,1 l Heller l 9 3,410,478 11/1968 Geisenhaver..417/366 [73] Ass1gnee: Danfoss A/S, Nordborg, Denmark F REI PA R L1[22] Filed: Mar. 31, 1971 o GN TENTS 0 App CATIONS 1,354,164 1/1964France [21] Appl. No.: 129,994

Primary Examiner-Manuel A. Antonakas Related Application DataAttorney-Wayne B. Easton [63] Continuation of Ser. No. 836,118, June 24,1969,

abandoned. [5 7] ABSTRACT The invention relatesto a lubricating systemfor a motor com- [52] U.S. Cl ..184/6.l6, 184/6. 1 8, 308/ l 34. lressmassembly, The, assembly has an oil sump and the motor 415/88compressor unit has vertically extending shaft means with a [51] Int. Cl..F16n 7/18 n r l lubricating bore, h lower part f the shaft means 58Field 0! Search 184/616, 6.18; 308/ 1 34. 1; being disposed in the pwith the mouth of the bore being in 45/88 fluid communication with thelubricating oil in the sump. The

mouth of the shaft bore is provided with a propeller to effect anincreased rate of lubricating oil delivery.

1 Claim, 3 Drawing Figures OIL PUMPFORA MOTOR COMPRESSOR Thisapplication is a continuation of Ser. No. 836,1 l8, filed June 24, 1969and now'abandoned.

The invention relates to an oil pump for a motor compressor having a.vertical motor-shaft, through the bore of which oil is delivered to thepoints where it is to be used, and the lower end of which extendsintoanoil sump and is provided with a solidly built-in insert for increasingthe delivery of oil.

Such oil-pumps are used for example for lubricating and cooling encasedmotor compressors for small refrigerating machines. In a known oil-pump,the lower. end of the shaft, extending-into the oil sump, consists of afrusto-conical hollow portion. The oil is entrained through frictionby'the wall of the cone and is carried upwards long the inside wall ofthe cone by centrifugal force. A body of oil, defined by a'paraboloid,is then formed in the interior of theshaft, and oil from this body ispassed to the points where it is to be used with thehelp of furtherdelivery means, or without such help if the'pressurelevel of the oil isitself sufficient. In this connection, it is also known to fit anaxially parallel sheet-metal element in the lower end of the hollowcone, the function of which element is to set the oil in rotation morerapidly and thereby to increase the pressure-level that can be producedwith the help of the hollow cone. Here, a certain limit forpressure-level or quantity of oil delivered cannot be exceeded, sincethe geometrical dimensions of thehollowcone are fixed to a large extent,in particular, the upper cross-section by the cross-section of theshaft, and the lower cross-section by a minimum inlet orifice.

The object of the invention is to achieve a'higher pressurelevel and/ora greater delivery quantity in an oil-pump of the originally describedkind.

According to the invention this object is achieved by the insert takingthe form of a propeller having a vertically disposed axis.

This sheet-metal propeller insert imparts drive to the oil not only inthe circumferential direction but in the axial direction too. Thecircumferential movement can, in conjunction witha hollow cone, beutilized to increase the centrifugal'pumping action, and the axial drivecontributes directly to increasing the pressure. Since the shaft rotatesat a high speed, e.g. at 3,000 r.p.m., the forces applied to the oil areconsiderable.

In a further form of the invention, the shaft can be fonned atthe bottomas a cylindrical tube which, at its lower end, ac-

commodates the propeller-like insert of roughly the same diameter. Asagainst the hollow cone, such a tube not only has the advantage of beingof simpler shape, but it also has a larger inlet orifice, so that, for alikerate of flow, a larger quantity of oil can enter. The loss indelivery capacity resulting from the non-use of a hollow coneisconsiderably more than compensated by the fact that a propeller havinga relatively large diameter can be used. This results in a-pump thatdelivers a large quantity of oil and operates at a high deliverypressure.

A particularly simple construction is obtained if the motorshaftconsists of two parts inserted in the bore of the rotor, the upper ofwhich parts carries the crank and the lower one constituting anoil-delivery pipe. In this way, practically the entire cross-section ofthe bore of the rotor is available for'delivering the oil.

In a further form of the invention, the outside circumference of thetube can have a shoulder which alone, or by means of a disc fittedthereon, forms a stop limiting the extent to which the tube can bepushed into the rotor. This renders assembly easier, since the positionof the inserted part is accurately predetermined by this shoulder.

The stop can also lie on the short-circuiting ring of the rotor and canseal off an annular distributing chamber which communicates with theinterior of the tube through openings in the tube and from whichpassages lead to the upper side of the rotor. Because of the highdelivery capacity of the oil-pump, a considerable amount of surplus oilis available for cooling the statorwinding. This surplus is passedthrough the annular distributing chamber and the passages in the rotor,which offer relatively little resistance, and is flung over the statorcoil-ends at the upper side of the motor. The remaining stream of oil,

which passes in the interior of thehollowmotor-shaft, is unaffected bythis.

The invention will now be described inmore detail by reference toembodiments illustrated in the drawing, wherein:

FIG. 1* shows a longitudinal section through anencased motor compressorincorporatingthe oil-pump of the'invention,

FIG. 2 is a-planview of the propeller-like sheet-metalinsert, and

FIG. 3 shows a portion of a modified form of construction.

A carrier element 2is supported in a case 1 by means of springs, notillustrated. The carrier element supports the stator 3' of an electricmotor, incorporates a bearing 4 for the motor crankshaft Sand, togetherwith an extension 6, forms, on the one hand, noise-reducing, chambers 7and, on the other, a cylinder, not illustrated, the axis of whichextends at right-angles to the plane of the drawing. An insert 8 closesthe noisereducing chambers7 and formsasecond bearing 9. A backing platellJand a centrifugingplatel2are fitted at the upper end of the shaft 5by meansof a screw-bolt 10. At its crank 13, the shaft carries a crankbearing 14, which is linked to the connectingrod of the-piston- Therotor l5' of the motor has an upper short-circuiting ring 16 and alowershort-circuiting-ring 17'. The stator has upper coil-ends l8 andlower coil-ends 19. The bore 20 of the rotor is shrunk on to the shafts.A cylindrical tube 21 is inserted from below into the bore 20, this tubeconstituting an extension of the motor-shaft and acting-as theoil-delivery means. The tube has an outer shoulder 22, which carries adisc 23, which bears against the lower short-circuiting ring 17 of therotor. Precise positioning of the tube 21 when fitted is thus ensured.

Providedat the lower end of the tube 21 is a propeller-likesheet-metal'insert which can be simply pressed into the tube 21; Inthepresent embodiment, this insert consists of a sheet-metal disc whichcontains radial slots 25 at intervals of 90, the parts between the slotsbeing inclined as in a propeller.

Thetube extends into the=oil sump 27. Oil supplied by the propeller24'risestl1rough-the-interior'28 of the tube and the borer29 of theshaft 5. Runningfrom the bore 29 are a crossbore 30,forlubricating'the-bearing 4, and three parallel bores 31, 32land33whichzterminate'at the top near the plate 12. A cross-passage-forlubricating thecrank bearing 14 can branch from the bore 31, andacross-passage for lubricating the bearing 9 branches from the bore 33.Thesurplus oilcomes out at v the top intothe plate lZand is flung on' tothe wall of the case l alongwhich itruns back into the sump 27 and iscooled in so doing.

The tube 21 also contains holes 34*opening into an annular distributingchamber 35 which is formed between the tube 21, the rotor 15, theshort-circuiting ring- 17 and the disc 23. Passages 36 in the rotorextend upwards from this chamber. Theseterminate in a chamber 37.The'oil delivered to this point is flung outwards by the uppershort-circuiting ring 16 and strikes the upper coil-ends='l8-, therebycooling them. The oilthen flows back into the sump=27l The pipe21 andthe propeller-like insert 24' deliver so great a quantity of oil thatadequate lubrication takes place, the stator coil ends are cooled and,furthermore, a certain quantity of oil is circulated in such manner thatthe oil flowing down over the-wall of the case is cooled and the meanoil temperature is thus kept low.

FIG.'3 shows how the tube 21 can alsobe pushed by its shoulder 22directly'against the lower end-face of the stator 15 was to define theposition of the tube. A slight depression of, for example, 0.2 mm, issufficient for forming the shoulder.

In some cases it is also of advantage for the tube itself to be providedwith a fairly thick flange which acts as a stop on the short-circuitingring 17. The bores 34 can then be contained in this flange and canextend obliquely upwards, so that a still further delivery action isobtained.

We claim:

shaped sheet metal propeller mounted in the mouth of said bore, saidpropeller having a diameter equal to the diameter of said bore andhaving a plurality of radially extending vanes separated by radiallyextending slots with each of said vanes being inclined relative to theaxis of said bore.

1. A motor compressor assembly comprising a housing, a combined motorand compressor unit in said housing, a common frame for said unit,vertical motor and compressor shaft means journalled in said frame, anoil sump in the lower part of said housing, said shaft means having acentral lubricating bore in fluid communication with said sump, agenerally disk shaped sheet metal propeller mounted in the mouth of saidbore, said propeller having a diameter equal to the diameter of saidbore and having a plurality of radially extending vanes separated byradially extending slots with each of said vanes being inclined relativeto the axis of said bore.